Fuse



March 25, 1930. A. G. STEINMAYER l Filed April 2, 1928 www' PatentedMaf. 2s, 1930 UNITED STATES PATENT ori-Ica ALWIN G. STEINMAYJER, OFMILWAUKEE, WISCONSIN, ASSIGNOR, BY 'MESNE .ASSIGN- MENTS, T LINEMATERIAL COMPANY, 0F SOUTH MILWAUKEE, WISCONSIN, A. COR- PORATION 0FDELAWARE FUSE Application led April 2, 1928. Serial No. 266,614.

-difculty in that the relatively high voltages require extremely fastvolatilization of the fuse element whereas with voltages of acomparatively lower value it is essential that the speed ofvolatilization be materially reduced,

to insure enough of the element being burned away to prevent thepossibility of current leakage and to this end it is desirable that thetube be of comparatively small internal diameter when the voltage ishigh so as to increase the speed of volatili'zation and larger,

kwhen the voltage is relatively low so that the speed of volatilizationis reduced.

Therefore, it is an object of this invention to provide a fuse of thecharacter described which is so constructed as to be equally adaptablefor use with either low or high voltages.

Another object of this invention resides in the provision of a fuse ofthe character described in which the tube has a plurality of insidediameters.

And a further object of this invention resides in the provision of afuse ofthe character described in which the tube has a relatively smalldiameter for a portion of its length and a larger inside diameterthroughout the remainder of its length, the reduced section or point ofinitial rupture of the fuse element being positioned within the portionhaving the small diameter.

With the above and other' objects in viewl which will appear as thedescription proceeds, my invention resides inthe novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly dened by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention maybe made as come within the scope of theclaims.

In the accompanying drawing, I 'have 11- V`.to-.approach each other.

lustrated one complete example of the physical embodiment of myinvention constructed according tothe best mode I have so far `devisedfor the practical application of the principles thereof, and in which:

The single gure is a transverse sectional yiew taken through a fuseembodying my invention.

Referring now more particularly to the accompanying drawing, numeral 5designates a tube of insulating material preferably bakelite or fibrehaving a bore 6 of relatively small diameter extending for approximatelyone fourth its length and a larger boref'l extending throughout theremainder of its length.

having the smaller inside diameter and a second contact 9 is secured onthe tube at a medial point, the contacts being electrically connected bya fuse element 10 and' forming means by which the fuse is connected withan electric circuit, not shown.

The Contact 8 is provided with an upwardly extended projection 11 whichis centrally bored, as at 12 to register with the bore 6 and isexternally threaded to receive a cap member 18, between the end wall ofwhich and the outer face of the projection 11 the head of asubstantially l shaped portion 14 formed by bending the adjacent end ofthe fuse element, is impinge'd to thus electrically connect the elementwith the Contact 8; the other end of the element being connected withthe contact 9.

The contact 9 is provided with an annular ange 16 which is externallythreaded to receive a collar member 17 and that portion of the contactextended beyond4 the Hange 16 is taperingly reduced, as 'at 18. Thecollar member 17 has an inwardly extending annular flange 19, theperipheral wall or bore 20 of which is correspondingly tapered so thatthreading of the collar member onto the flange 16 causes the taperedfaces 18 and 20 The fuse element extends through the open end of thetube and is then directed back on itself, the end 15 thereof extendingupwardly to be passed between the tapered faces 18 and 20 to be securelyclamped therebetween and thus electrically sel . of reduced crosssectional area which is located adjacent the contact 8 within the bore 6so that upon an overload the initial rupture of the element takes placewithin the bore of smaller diameter, and if the voltage with which thefuse is being used is relatively high, the volatilization is suiicientlyrapid due to the restricted area of the bore, thus preventing damage tothe equipment, or the fuse itself. Likewise, if the voltage with whichthe fuse is used is relatively low, the larger diameter of the tubeautomatically compensates for the rapid volatilization which takes placewithin the smaller bore and permits the fuse element to burn away at asuiiciently low speed to insure the entire element rrbeing destroyed.

If desired, a tube 22 may be extended from the collar member 17 toenclose the lower end of the tube 5 and the upwardly directed portion orend 15 of the fuse element. It will also be understood that the tube 5may be formed of two separate units or sections, one of smaller and theother of larger diameter.

What I claim as my invention is:

1. In an expulsion fuse of the character described, a tube having a boreof relatively small diameter extending throughout a portion of itslength and a bore of greater diameter extending throughout the remainderof its length, sald bore of greater diameter being unrestrictedly opentothe atmosphere, contacts carried by the tube, and a fuse ele-- mentpositioned within the tube bores and electrically connected with thecontacts.

2. An expulsion fuse comprising a tube having bores of dierent diametersand having one end unrestrictedly open to. theY atmosphere, a pair ofcontacts, and a fuse element within the tube and electrically bridgingthe contacts.

3. In an expulsion fuse of the character described, a tube having a boreof relatively small diameter and a bore of greater diameter, said boreof greater diameter being unrestrictedly open to the atmosphere,contacts carried by the tube, and a fuse element electrically connectedwith the contacts and positioned within the bores of the tube the fuseelement having a portion of reduced cross sectional area, which ispositioned within the bore of small diameter whereby initial rupture ofthe fuse element takes place within the bore of smaller diameter.

4. In an expulsion fuse of the characterldescribed, a tube having boresof different diameters, the bore of greater diameter being directly opento the atmosphere, a contact connected with the tube adjacent the boreof smaller diameter, a second contact adjacent the other end of thetube, and a fuse element having one end connected with the firstmentioned contact and its other end passed outwardly through the openend of the tube and electrically connected with the second contact, thefuse element having a portion of reduced cross sectional area-disposedwithin the bore of smaller diameter whereby the vol-

